The invention relates to a constructional unit comprising a metal weld stud, which has a shank covered by a plastic cap, to a method of removing a cap from the shank of a metal weld stud as well as to a device for effecting the method.
A constructional unit comprising a metal weld stud and a plastic cap is known from U.S. Pat. No. 4,799,842. The weld stud has a region which is adjoined by a shank -of a smaller diameter so as to form a step. A cap is disposed up to contact with the step on the shank. The cap has a surface.
Such a weld stud may be welded to a component, the stud welding being effected by a known welding device, in particular a welding gun, which by means of clamping jaws grasps the weld stud at its region between the shoulder and the end face to be welded.
The cap performs the function of protecting the shank from possible external influences when a structure, to which the weld stud has been welded, is subjected to further treatment or machining stages. Such a weld stud may form, for example, a grounding stud on a body of a motor vehicle.
During painting of the vehicle body, the cap remains fitted on the weld stud. Once painting has been effected, the cap may be removed from the weld stud, with the result that the shank is not coated with paint. From U.S. Pat. No. 4,799,842, it is known for the cap to be unscrewed from the shank, which has a thread. To said end, the cap has radially projecting wings.
A further construction of a constructional unit comprising a metal weld stud and a cap is known from German Utility Model G 94 13 406.5. In the case of said constructional unit also, the cap is unscrewed from the shank of the weld stud. To said end, the cap has a tool engagement region on its outer surface.